Multiple Motors And Dual Speed Motors On Soft Starters

Hi

I have an application where we are trying to determine if a soft starter could be used to ramp from low speed to high speed on a dual speed motor. The dual speed motor has six terminals with two star connected windings, one for low (8 pole) and one for high (2 pole) - not a dahlander type.

The setup would include a low speed contactor (on output of starter), high speed contactor (on output of starter), motor parameter (low/high) input, low and high start relays. The contactors and relays would be interlocked as to avoid being on at the same time.

Does anyone have experience with such an application or can point out any problems that might arrise from this configuration?

I can see that switching between the two speeds at stop shouldn't be a problem but switching to the high speed whilst the motor is already running... I'm not sure.

Thanks,

Leigh

Soft Starter Settings For Centrifugal Pump Application

Hello everyone,

I've been reading this forum for some time trying to improve my knowledge base, thanks to everyone who posts answers, now I have a question of my own.

I have to set up a soft starter for a 30kW centrifugal pump. I have two options for the start curve, a flat current limit start with soft start turned off or the soft start curve that ramps the current up over time.

I'm trying to determine which type of start curve is best for a centrifugal pump with high resistive starting torque? Or how should I determine which start curve is best?

If I start the pump with a flat current limit start I imagine the pump will ramp up very rapidly after the initial resistance is overcome and if I start it with a current ramp I'm concerned I won't get the required starting torque.

Thanks, Leigh